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West Nile virus (WNV) preferentially infects neurons and produces virulence factors that can potentially cause long-term neurological sequelae. These virulence factors are hypothesized to be associated with formation of virus-induced membrane structures (IMS), which protect the virus replication complexes (RCs) from the host defense systems. Our long-term goal is to elucidate the regulatory mechanisms controlling the formation of IMS as a prerequisite to the development of a therapeutic approach that can be used to disrupt the disease process.

Central hypothesis

WNV nonstructural (NS) 4B (NS4B) protein is a major regulatory initiator controlling the aggregation of the membranous vesicles (MV) in generating the IMS. This hypothesis is based on the following observations: (1) NS4B is a highly membrane-associated protein localized to the IMS, (2) NS4B is an inhibitor of the IFN-alpha/beta response, (3) mutations in the central region of NS4B result in attenuated or passage-adapted mosquito-borne viruses suggesting the vital role this protein plays in replication and pathogenesis, (4) mutation in WNV NS4B attenuates the IMS formation and confers highly attenuated phenotype in mice.

Objective

To determine if WNV NS4B is an appropriate target for the development of antiviral drugs capable of attenuating the virulence of WNV.

Specific Aim 1

Demonstrate that WNV NY99 strain NS4B is a major regulatory initiator of the IMS formation.

Specific Aim 2

Demonstrate that the central region of NS4B is critical for the initiation of the MV aggregation to increase their efficiency in viral replication.

Significance

The continued global reemergence of WNV virulent strains emphasizes the need to identify therapeutic targets for anti-WNV drug design. Successful accomplishment of the two aforementioned specific aims will provide the foundation to evaluate high-throughput screening assays for WNV pharmacologic inhibitors. The newfound knowledge will have significant impact in developing therapeutic interventions for WNV and other re-emerging mosquito-borne pathogens, such as dengue virus.